Economical, efficient and reliable automated methods of removing liquid and semiliquid manure from barns or other animal housing structures have been the subject of many inventions over the years. Early systems used simple paddle conveyor systems for pushing or pulling the manure at or above ground level out of a building, along gutters or troughs formed in the building floor, or by using belt conveyor-type structures. More recent techniques have found it advantageous to directly pump the manure from a building through underground conduits, to remotely located storage reservoirs or collection sites. Such systems typically utilize collection hoppers located below the building's floor, into which manure and waste from the building's floor is pushed or scraped. Reciprocating hollow piston pumps have typically been used to force the manure from the collection hoppers into the underground conduits, for transport through the conduit to the remotely located collection sites.
The general principles of such manure transfer techniques and a detailed description of a pumping system for accomplishing the transfer is described in U.S. Pat. No. 3,687,311, hereby incorporated by reference to the extent that such patent is needed to provide a background for this invention. The principles broadly described in that patent are still in use today. A number of variations of the basic concept have been configured over the years, primarily with respect to the piston and pump configurations used in such systems. For example, U.S. Pat. No. 3,876,341 describes such a system which utilizes a pair of vertically oriented pumps; whereas U.S. Pat. No. 4,439,115 describes a pump configuration that "pulls" the manure up from the bottom of the collection hopper and into the transfer conduit, rather than pushing the manure downwardly into the conduit.
While each different such system enjoys certain benefits over others, they all share the common principle of using a generally submerged pump cylinder and piston combination that may require repair from time to time. Heretofore, such repair has been very difficult and time consuming since the piston and cylinder are not readily removable from the collection hopper. Further, such removal can be dangerous, as for example, when a piston becomes wedged or stuck in the cylinder which would require removal of both the piston and its associated cylinder from the hopper. Since the pump cylinder in which the piston reciprocates generally has an outlet flapper valve that prevents back-flow of manure through the cylinder and back into the hopper, removal of the cylinder generally eliminates the back-flow safeguard. This can be particularly dangerous in situations wherein a clogged conduit has enabled manure gases within the conduit to create a back-pressure in the conduit, or in cases wherein there is a significant back-pressure head existing in the transfer conduit due to the fact that the manure is being transported and stored to a reservoir that is physically located higher than the conduit and collection hopper assembly. There have been instances in such situations wherein removal of the pump cylinder and piston has enabled back-flow of manure through the system with such force that it has entrapped operators in the collection hopper or caused them to become entangled in the pump assembly, and has resulted in the back-flow of thousands of gallons of material from the storage reservoir, back into the building. Similarly, the existence of pressurized gases within the line can create dangers to an operator, besides posing a problem due to their explosive nature.
Another problem not effectively addressed by prior art systems, is the handling of blockages in the transfer conduit. Such conduits often extend many hundred of feet below grade, and are only accessible through their respective ends. Due to the inconsistency of the manure and waste carried by the conduits, which most often includes straw and bedding material, such foreign materials have a tendency to compress in the transfer conduit when under pumping pressure, and to block the conduit. Such blockage "plugs" of up to 15 feet or more are commonly found. Most often, such blockages occur when there is significant back-pressure from the collection reservoir at the conduit outlet, caused by a relatively filled reservoir. While it is most desirable to empty the reservoir prior to clearing the blockage from the conduit, such emptying is not always possible under winter or severe environmental conditions.
To clear a plug from the line, it is often desirable to inject fluids under high pressure into the line to dislodge or break up the blockage plug. It is generally not feasible to enter the conduit through the storage reservoir discharge end. To be effective, such high-pressure jet should impinge directly upon the plug, which may require insertion of a high-pressure hose and nozzle into the conduit through the piston and cylinder. Such conduit entry through the piston/cylinder negates the back-flow safety feature of the cylinder, since the back-flow valve of the cylinder is held open by the hose running therethrough. If the system does not have an effective back-flow valve at the discharge end of the conduit, or if the discharge end is stuck open, once the plug is dislodged with the high-pressure jet, there is no means for preventing free back-flow from the reservoir, through the conduit and open cylinder/piston, back into the building.
Another tendency of such manure pump and transfer systems is their tendency to collect sediment and residue in the transfer conduit leading from the pump to the remotely located storage reservoir. Since such systems necessarily have slow flow rates of material through the conduit, sediment can collect relatively quickly, and provide restriction or blockage problems to the system. Other than for the same technique used with blockages, of feeding a high-pressure line through the pump/cylinder assembly and down through the line to flush the system, prior art systems do not provide any effective means for flushing such residue from the manure transfer line.
This invention addresses the above-described shortcomings of prior art systems. The unique system configuration of this invention allows back-pressure to be relieved within the transfer conduit and for ease of removal of material from the conduit so that the pump piston and cylinder can be accessed and/or safely removed for repair. The present invention also enables for high-pressure flushing of sediment from the conduit or for removing blockage plugs, without disabling the back-flow safety features of the pump cylinder mechanisms. As will become apparent upon a more detailed description of the present invention, such features and benefits are provided for manure pumps and systems of varied designs and configurations.